Viruses, either those occurring in nature or recombinant versions thereof, are used for vaccination and in the field of gene therapy. It is possible for many viruses or virus-like particles to safely and efficiently propagate these in host cells (see, for instance, WO 01/38362, which describes the propagation of various viruses in host cells being E1-immortalized retina cells). Recombinant adenoviruses are a preferred class of viral vectors for use in gene therapy and for vaccination purposes. Such recombinant adenoviruses are usually deficient in at least the E1 region, and are propagated in complementing cells providing the E1-region, such as 293 cells, or E1-immortalized retina cells, such as PER.C6® cells (see, for instance, U.S. Pat. No. 5,994,128, the contents of the entirety of which are incorporated herein by this reference).
After propagation of the viruses in the host cells, for virtually all applications it is necessary to purify the viruses from the host cells before further use.
International patent application WO 98/22588, the contents of the entirety of each of which are incorporated herein by this reference, describes methods for the production and purification of adenoviral vectors. The methods comprise growing host cells, infecting the host cells with adenovirus, harvesting and lysing the host cells, concentrating the crude lysate, exchanging the buffer of the crude lysate, treating the lysate with nuclease, and further purifying the virus using chromatography.
Several other publications describe the purification of viruses from host cells, mostly concentrating on the use of specific chromatographic matrices for purification of the virus from a host cell lysate, see, e.g., U.S. Pat. Nos. 6,008,036, 6,586,226, 5,837,520, 6,261,823, 6,537,793, and international patent applications WO 00/50573, WO 02/44348 and WO 03/078592, the contents of the entirety of each of which are incorporated herein by this reference.
Most of the described methods apply a nuclease treatment step to degrade DNA impurities. Despite the description of several processes regarding different chromatography matrices, a need remains for alternative, and preferably improved, methods for virus purification from host cell cultures.